James Wilson, more commonly known by his account name, UberHaxorNova or just Nova, is a YouTuber who plays games. He is one half of the Cow Chop duo, along with ImmortalHD. He is also a former member of a group called the Creatures (Other members are Kootra, Zeroyalviking, Sp00nerism, DanzNewz, SSoHPKC, ImmortalHD, Dexter Manning and GoldenBlackHawk).
A "fanwar" occures when fans of YouTube channels argue which YouTuber is best, in this case PewDiePie Vs Nova. Fans would go on to the channel they don't like and post comments favouring the channel they came from.
To end the fanwar PewDiePie and Nova said that they would be doing a collaboration of some sort while insisting that their fans not continue, PewDiePie posted on twitter and Nova said it on his Happy Wheels video.
In the end they played worms together with Cry and Sp00nerism, this stopped most of the fanwar. The collaboration sparked a lot of positive reactions from fans whom wanted more. However, PewDiePie lived in Italy at the time making it hard for him to collaborate because all other collaborators lived in the U.S.
On March 3, 2013 the first Worms' Revolution video was uploaded on Nova's channel, then on Sp00n's channel and on PewDiePie's channel. It featured PewDiePie & Cry vs. Nova & Sp00n in a match of Worms' Revolution.